lab-2l+(a-1)的平方=0
ab = 2
a = 1
b = 2
1ab+1(a+1)(b+1)+1(a+2)(b+2)+...+1(a+2008)(b+2008)
= 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + …… + 1/2009 - 1/2010
= 1-1/2010
=2009/2010
lab-2l+(a-1)的平方=0
ab = 2
a = 1
b = 2
1ab+1(a+1)(b+1)+1(a+2)(b+2)+...+1(a+2008)(b+2008)
= 1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + …… + 1/2009 - 1/2010
= 1-1/2010
=2009/2010